hi, don't you have to multiply the matrix from the left side with the vector, like this: M * x = x', whereas M is your 'WorldCoordsMatrix', x is your local BBox vector and x' is the same in world coords.
hope this helps. daniel Siddharth Palaniappan wrote: > Hi osg users, > > I'm currently using openscenegraph for my class project to simulate traffic. > I have a problem in that , i need to find collision detection between > consecutive cars and stop the car if there is a collision. I have followed > the osgExample- for animation. I have used an animationpath and > animationpathcallback and i have implemented my own spline interpolation for > the car to traverse on a spline. I tried to get the world coordinate of the > bounding box like this.. > > * i have a class Vehicle that stores the node to which an openflight model is > read into. > > * the leaf node is the node having the vehicle, the parent node of this node > is a transformation node which has an animationpathcallback set to, and this > also has a parent node to initially set the location and orientation, (just > like in the osgExample animation). > > * i have a node visitor that traverses parents..so it goes from the current > node to the root concatenating all the world coordinates. > > * then i get the local bounding box of the node and get the minimum and > maximum and multiply the world coord matrix with these points to form a new > min and max point and create a new bounding box. I do this for every two node > to check the intersection of two consecutive nodes. > > > //getWorldCoords() - forwards to a nodevisitor to get world coords matrix. > osg::Matrixd* WorldCoordsMatrix = getWorldCoords(this->m_Vehicle) ; > osg::BoundingBox VehicleBBox ; > > VehicleBBox.expandBy(m_Vehicle->getBound()) ; > > //Convert the vehicle local coords to world coordinates. > osg::Vec3f MinPt(VehicleBBox.xMin() , VehicleBBox.yMin() , > VehicleBBox.zMin()) ; > osg::Vec3f MaxPt(VehicleBBox.xMax() , VehicleBBox.yMax() , > VehicleBBox.zMax()) ; > > osg::Vec3f NewMinPt , NewMaxPt ; > NewMinPt = MinPt * (*WorldCoordsMatrix) ; > NewMaxPt = MaxPt * (*WorldCoordsMatrix) ; > > this->m_VehicleBoundingBox = new osg::BoundingBox(NewMinPt , NewMaxPt) ; > > I am not getting correct results. I get that the bounding boxes dont > intersect at all or sometimes intersect at odd places. Please let me know if > i'm doing something stupid or if i my understanding of anything wrong. > > > Thank you, > > Yours Sincerely, > > Siddharth > > > > > > > > ____________________________________________________________________________________ > Never miss a thing. Make Yahoo your home page. > http://www.yahoo.com/r/hs > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
